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<title>valtype::creditcard::discover - Validation types</title>
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<h1 class="doctools_title">valtype::creditcard::discover(n) 1 tcllib &quot;Validation types&quot;</h1>
<div id="name" class="doctools_section"><h2><a name="name">Name</a></h2>
<p>valtype::creditcard::discover - Validation for Discover creditcard number</p>
</div>
<div id="toc" class="doctools_section"><h2><a name="toc">Table Of Contents</a></h2>
<ul class="doctools_toc">
<li class="doctools_section"><a href="#toc">Table Of Contents</a></li>
<li class="doctools_section"><a href="#synopsis">Synopsis</a></li>
<li class="doctools_section"><a href="#section1">Description</a></li>
<li class="doctools_section"><a href="#section2">API</a></li>
<li class="doctools_section"><a href="#section3">Error Codes</a></li>
<li class="doctools_section"><a href="#section4">Bugs, Ideas, Feedback</a></li>
<li class="doctools_section"><a href="#keywords">Keywords</a></li>
<li class="doctools_section"><a href="#category">Category</a></li>
<li class="doctools_section"><a href="#copyright">Copyright</a></li>
</ul>
</div>
<div id="synopsis" class="doctools_section"><h2><a name="synopsis">Synopsis</a></h2>
<div class="doctools_synopsis">
<ul class="doctools_requirements">
<li>package require <b class="pkgname">Tcl 8.5</b></li>
<li>package require <b class="pkgname">snit 2</b></li>
<li>package require <b class="pkgname">valtype::common</b></li>
<li>package require <b class="pkgname">valtype::luhn</b></li>
<li>package require <b class="pkgname">valtype::creditcard::discover <span class="opt">?1?</span></b></li>
</ul>
<ul class="doctools_syntax">
<li><a href="#1"><b class="cmd">valtype::creditcard::discover</b> <b class="method">validate</b> <i class="arg">value</i></a></li>
<li><a href="#2"><b class="cmd">valtype::creditcard::discover</b> <b class="method">checkdigit</b> <i class="arg">value</i></a></li>
</ul>
</div>
</div>
<div id="section1" class="doctools_section"><h2><a name="section1">Description</a></h2>
<p>This package implements a snit validation type for a Discover creditcard number.</p>
<p>A validation type is an object that can be used to validate Tcl values
of a particular kind.  For example, <b class="cmd">snit::integer</b>, a validation
type defined by the <b class="package"><a href="../snit/snit.html">snit</a></b> package is used to validate that a
Tcl value is an integer.</p>
<p>Every validation type has a <b class="method">validate</b> method which is used to
do the validation. This method must take a single argument, the value
to be validated; further, it must do nothing if the value is valid,
but throw an error if the value is invalid:</p>
<pre class="doctools_example">
    valtype::creditcard::discover validate .... ;# Does nothing
    valtype::creditcard::discover validate .... ;# Throws an error (bad Discover creditcard number).
</pre>
<p>The <b class="method">validate</b> method will always return the validated value on
success, and throw the <b class="cmd">-errorcode</b> INVALID on error, possibly
with additional elements which provide more details about the problem.</p>
</div>
<div id="section2" class="doctools_section"><h2><a name="section2">API</a></h2>
<p>The API provided by this package satisfies the specification
of snit validation types found in the documentation of
<i class="term"><a href="../snit/snit.html">Snit's Not Incr Tcl</a></i>.</p>
<dl class="doctools_definitions">
<dt><a name="1"><b class="cmd">valtype::creditcard::discover</b> <b class="method">validate</b> <i class="arg">value</i></a></dt>
<dd><p>This method validates the <i class="arg">value</i> and returns it, possibly in a
canonical form, if it passes. If the value does not pass the
validation an error is thrown.</p></dd>
<dt><a name="2"><b class="cmd">valtype::creditcard::discover</b> <b class="method">checkdigit</b> <i class="arg">value</i></a></dt>
<dd><p>This method computes a check digit for the <i class="arg">value</i>. Before doing
so it is validated, except for a checkdigit. If the value does not
pass the validation no check digit is calculated and an error is
thrown instead.</p></dd>
</dl>
</div>
<div id="section3" class="doctools_section"><h2><a name="section3">Error Codes</a></h2>
<p>As said in the package description, the errors thrown by the commands
of this package in response to input validation failures use the
<b class="cmd">-errorcode</b> INVALID to distinguish themselves from package
internal errors.</p>
<p>To provide more detailed information about why the validation
failed the <b class="cmd">-errorCode</b> goes actually beyond that.
First, it will contain a code detailing the type itself. Here this is
<b class="const">CREDITCARD DISCOVER</b>. This is then followed by values detailing the
reason for the failure. The full set of <b class="cmd">-errorCode</b>s which can
be thrown by this package are:</p>
<dl class="doctools_definitions">
<dt>INVALID CREDITCARD DISCOVER CHARACTER</dt>
<dd><p>The input value contained one or more bad characters, i.e. characters
which must not occur in the input for it to be a Discover creditcard number.</p></dd>
<dt>INVALID CREDITCARD DISCOVER CHECK-DIGIT</dt>
<dd><p>The check digit of the input value is wrong. This usually signals a
data-entry error, with digits transposed, forgotten, etc. Of course,
th input may be an outright fake too.</p></dd>
<dt>INVALID CREDITCARD DISCOVER LENGTH</dt>
<dd><p>The input value is of the wrong length to be a Discover creditcard number.</p></dd>
<dt>INVALID CREDITCARD DISCOVER PREFIX</dt>
<dd><p>The input value does not start with the magic value(s) required for it
to be a Discover creditcard number.</p></dd>
</dl>
</div>
<div id="section4" class="doctools_section"><h2><a name="section4">Bugs, Ideas, Feedback</a></h2>
<p>This document, and the package it describes, will undoubtedly contain
bugs and other problems.
Please report such in the category <em>valtype</em> of the
<a href="http://core.tcl.tk/tcllib/reportlist">Tcllib Trackers</a>.
Please also report any ideas for enhancements you may have for either
package and/or documentation.</p>
<p>When proposing code changes, please provide <em>unified diffs</em>,
i.e the output of <b class="const">diff -u</b>.</p>
<p>Note further that <em>attachments</em> are strongly preferred over
inlined patches. Attachments can be made by going to the <b class="const">Edit</b>
form of the ticket immediately after its creation, and then using the
left-most button in the secondary navigation bar.</p>
</div>
<div id="keywords" class="doctools_section"><h2><a name="keywords">Keywords</a></h2>
<p><a href="../../../../index.html#checking">Checking</a>, <a href="../../../../index.html#discover">Discover</a>, <a href="../../../../index.html#testing">Testing</a>, <a href="../../../../index.html#type_checking">Type checking</a>, <a href="../../../../index.html#validation">Validation</a>, <a href="../../../../index.html#value_checking">Value checking</a>, <a href="../../../../index.html#bank">bank</a>, <a href="../../../../index.html#card_for_credit">card for credit</a>, <a href="../../../../index.html#credit_card">credit card</a>, <a href="../../../../index.html#finance">finance</a>, <a href="../../../../index.html#isa">isA</a></p>
</div>
<div id="category" class="doctools_section"><h2><a name="category">Category</a></h2>
<p>Validation, Type checking</p>
</div>
<div id="copyright" class="doctools_section"><h2><a name="copyright">Copyright</a></h2>
<p>Copyright &copy; 2011 Andreas Kupries &lt;andreas_kupries@users.sourceforge.net&gt;</p>
</div>
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